Blender 2.75 Time Node
I think what you mean is a node that does the same thing as the time node in the compositor.  Unfortunately there is no single cycles node that does this.  However one can be constructed rather easily.

First add a value node and plug it into the color on an RGB curves node.  Then keyframe the value node's value to be 0 at frame 1 and 1 at the last frame.


Then select the value node and hop over to the graph editor...


... select the keyframes, press T, and select linear interpolation.


The output of the RGB curves node will be the same as the output of the time node would be in the compositor.  You could eliminate the RGB curves node and just edit the interpolation curve in the graph editor; but while that will give you a little more control it would be more cumbersome to tweak.  But it is an option if you need the extra control.